Haven't tried this myself but I think it should be possible:

• Upload the file to S3 using the S3Uploader, obtain the url
• Put the url in the message body of a tweet with the DirectTweeter

I'm not sure whether that will automatically shorten the url, if not you may need to run it through a url-shortening service before putting it in the tweet.

This article should give you some pointers.

You cant attach but as Hans said you can upload it somewhere else and provide a link to it

Thanks Hans, your method is valid though i was searching for a way to have it from within twitter ...